No longer the just adornment of ecology professors and battle re-enactors, now men in all walks of life are proudly displaying their facial hair.

It is one of the most apparent physical differences between Men and Women. In a species that long ago shed their body hair, Male facial hair didn’t just remain, it flourished.

It is a question that has deep implications for your understanding of Masculinity.

Why do Men have beards?

To find an answer, we need to look at what first makes a face ‘masculine’.

The shot of androgens around puberty encourages the development of Masculine facial characteristics. Brow ridges, lower and wider jaw development, thicker eyebrows, cheekbones, and of note for us, an abundance of facial hair. This is the result of a complex interplay between androgens, oestrogens and growth hormone But essentially, facial masculinity is associated with circulating Testosterone (6).

A stereotypical Masculine face is easy to visualise. A well developed jaw line, enhanced by lusty beard growth, strong brow lines and prominent cheekbones. These facial traits have even been shown to correlate with actual physical strength (1)

All very well, but why has this evolved to be so? After all, why would natural selection choose Men with hairier faces? If it was to keep them warm, surely women would have evolved beards too!

The obvious explanation is reasonably simple. Sexual selection.

Darwin proposed sexual selection as an element of his theory of Natural Selection. Effectively, if one sex consistently choses a particular trait in the other sex (e.g. facial hair), then the chosen individuals will pass their genes on to the next generation. In this way, the trait becomes established.

Why though, would Females choose a beard?

Well, if that trait is an external marker of the individuals fitness, or good genes, then it gives her the heads up that she is mixing her genes with the best she can find on the market. Interestingly, Testosterone is immunosuppressive. (2) That is, it makes it harder for the immune system to work well. So, a Male with high Testosterone needs good genes to thrive. By choosing a masculine face adorned with a beard, a Female has a clear indication she is mixing her genes with a partners genes that are also good.

Sounds great, except for one thing. Women just don’t seem to agree.

Firstly, Female preference for ‘masculine’ faces varies across their menstrual cycle. They also change their preferences if they are seeking a long term or short term relationship (3,9). Beard choice can vary across cultures and further, a female preference for just a moderately Masculine face is often noted (7, 9). In this way, Females probably mitigate against Males having ever higher levels of Teststerone with each generation. A sensible ploy, since very high testosterone Men are prone to commit less to child care, relationships, and have a propensity to do dangerous things and get themselves killed!

Secondly, Women have recently been shown to be attracted to the facial hair pattern that is less prevalent in a population (8). That is they will often be drawn to a man that is not following the crowd.

Something else other than Female choice clearly drove evolution of the Beard.

Look no further than COMPETITION.

Intrasexual selection is the process by which members of the same sex, compete, for access to members of the opposite sex.

Remember, it may be easy to see in a modern world how mate choice or sexual selection could drive evolution. Women choosing Men, Men choosing Women, all for various preferences. The fitness and beauty industry clearly illustrate some of these preferences and the market reflects the desire for them.

But this is not the same as the environment humans evolved in. Males could exclude other males by force or the very real threat of force. (11) There was no burly doorman or law enforcing policeman to step in when things started getting, excuse the pun, hairy. So while sexual selection, in this case Female choice, no doubt drove the evolution of some Male traits, a large part of what makes up a man today has been the result of competition with other Men. Facial hair included.

Beards signal dominance through association with Testosterone levels by increasing the relative appearance of the jaw, another attribute dependant on Testosterone for its development. Men with beards are rated as more socially dominant. (11)

Men judging other Men are most aware of the Masculine threat and aggressiveness signalled through beards (10) and perceived masculinity rises linearly with facial hair (7).

There are strong associations between beards and perceptions of social dominance, threat and aggression. Unsurprisingly, in modern situations where males have to compete more for resources, wearing a beard becomes more prevalent. For example, when more Men compete for Women in a crowded marriage market. (11)

In addition to facial hair many other traits likely evolved in response to intense competition with other Men. The modest average stature and body massdimorphism between human Males and Females (8% and 15% respectively) does not tell the full story. Corrected for fat free mass, Men are 40% heavier, and have on average 60% more lean muscle than women. Further, this mass is skewed to around 80% more arm muscle mass than women, similar in ratio to Male and Female Gorillas, the most sexually dimorphic* of all living primates. (11) This translates into striking physical differences in functional performance. An average human male is, by default, stronger than 99% of females.

I do not need to reach to the scientific literature to illustrate why. Men are more aggressive, fight more, commit more homicide and as a consequence suffer more traumatic injuries than women, particularly to the face as a result of blunt trauma. The relatively greater upper body mass compared to lower body mass in particular, suggests an evolutionary history of fighting. (13)

No wonder Men develop more robust facial structures and jaw bones around puberty. They are constructed to help withstand potential blows to the head.

It struck me in writing this that is not just in Humans that Male competition has driven unusual and lustrous hair growth.

The King of the Beasts also possesses a hirsute Male trait. A trait that grows at the onset of sexual maturity, is linked to Testosterone levels and indicates social dominance. The Lions Mane.

Could it be that Lions evolved a Mane for similar reasons as Humans?

A foray into the available evidence suggests this is very possible.

Lions are the only social cat species, and Male Lions compete vigorously to monopolise prides of females.

Male lions assess the darkness and length of others manes and avoid individuals they establish are stronger and fitter than themselves, helping them mitigate the costs of fighting. Those Lions who possess longer, darker Manes have higher testosterone levels, are socially more dominant and enjoy longer reproductive success. (14,16)

One author even draws the same parallel as we have here. That the Beard is to Men what the Mane is to the Lion. In fact, they develop the idea one step further. That the beard, like the mane, evolved as an adaptive attempt at structural protection. To help mitigate damage to face and neck area in violent conflict. (15)

Regardless of the theories of mane evolution, Mans legacy is inescapable.

Men are in their very essence, competitive beings, born out of thousands of generations of ancestors who competed and won in a game far, far more dangerous than the one most Men find themselves in now.

Your facial hair is an emblem of that past battle.

You can reject this notion and avoid competition. That is losing by default.

Or you can embrace it, grasp the joy of full blooded competition, and revel in the energy that is manifested when innate purpose synergises with decisive action.

Should you lose, then you have been gifted with the ultimate and most honest feedback. What better than defeat to teach you how to dust yourself off, fortify your resolve, and return to the arena a better Man?

Should you win, then a natural positive feedback loop will drive your Testosterone levels higher (12), ensuring more confidence, more action and ultimately more competition.

Virtue is rewarded in this world, remember. Natural law makes no false judgements. Its decisions are just and true, even when dreadful. The victor gets the gold and the land every time. He also gets the fairest maidens, the glory tributes. And - why should it be otherwise? Why should the delights of life go to failures and cowards? Why should the spoils of battle go to the unwarlike? That would be insanity, utterly unnatural and immoral.